fix(core): pass local profile dir as Chrome flag

[luochen211]

Summary

• pass local browser userDataDir as a Chrome flag instead of a chrome-launcher option
• preserve generated profile directories while avoiding WSL path conversion in launcher filesystem operations
• add focused v4 regression coverage for launch arguments

Fixes #1503

Tests

• pnpm --filter @browserbasehq/stagehand-extension build
• pnpm --filter @browserbasehq/stagehand build
• TypeScript SDK unit suite: 188/188 tests
• oxfmt --check and oxlint on changed TypeScript files
• git diff --check

[changeset-bot]

🦋 Changeset detected

Latest commit: 289eeca

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 5 packages

Name	Type
@browserbasehq/stagehand	Patch
@browserbasehq/stagehand-integrations	Patch
@browserbasehq/stagehand-integrations-example-eve-facade	Patch
@browserbasehq/stagehand-integrations-example-mastra-facade	Patch
@browserbasehq/stagehand-integrations-example-vercel-ai-facade	Patch

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[github-actions]

This PR is from an external contributor and must be approved by a stagehand team member with write access before CI can run.
Approving the latest commit mirrors it into an internal PR owned by the approver.
If new commits are pushed later, the internal PR stays open but is marked stale until someone approves the latest external commit and refreshes it.

[cubic-dev-ai]

No issues found across 3 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

Architecture diagram

sequenceDiagram
    participant Test as Regression Test
    participant Launch as launchLocalChrome()
    participant Flags as ChromeFlags Builder
    participant Launcher as chrome-launcher

    Note over Test,Launcher: Launch flow

    Test->>Launch: call with userDataDir option
    Launch->>Flags: build chromeFlags array
    Flags->>Flags: append "--user-data-dir=<path>"
    Flags-->>Launch: chromeFlags list
    Launch->>Launcher: launch({ chromeFlags, ignoreDefaultFlags })
    Note over Launch,Launcher: userDataDir NOT passed to launcher
    Launcher->>Launcher: start Chrome with flags
    Launcher-->>Launch: browser instance

    Note over Test,Launcher: Assertion path

    Test->>Launch: getLaunchArgs() captures launcher options
    alt userDataDir option absent from launcher
        Test-->>Test: expect args.userDataDir to be undefined
    end
    alt chromeFlags contains user-data-dir
        Test-->>Test: expect "--user-data-dir=<path>" in flags
    end

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_{Re-trigger cubic}

[luochen211]

Retargeted this PR to v3: main moved to Stagehand v4 in #2671 and removed the v3 core launcher, while v3 is now the maintained base for this code. The PR is mergeable again and its diff remains limited to the original launcher fix, regression test, and patch changeset.\n\nValidation against current v3:\n- pnpm --dir packages/core run gen-version\n- pnpm --dir packages/core run build-dom-scripts\n- pnpm --dir packages/core run build:esm\n- targeted Vitest: 13/13 tests\n- pnpm --dir packages/core lint\n- git diff --check

[luochen211]

Follow-up after inspecting the v4 replacement: main now implements local launch in packages/sdk-ts/src/browser/localBrowser.ts, but still passed userDataDir through chrome-launcher, so the WSL2 path-conversion bug remained. I therefore kept this PR on main and replayed the fix on the v4 path rather than reviving deleted v3 files.\n\nCurrent diff against main is only:\n- v4 local browser launcher fix\n- focused unit regression test\n- TypeScript SDK patch changeset\n\nValidation:\n- focused tests: 2/2\n- TypeScript SDK unit suite: 188/188\n- extension + TypeScript SDK builds (including publint)\n- targeted oxfmt + oxlint\n- git diff --check